Turkey announced today that it is ordering all Syrian diplomats and their staffs out of the country, as it joins other nations in registering outrage about a massacre over the weekend that has been blamed on forces loyal to Syrian President Bashar Assad.

While Turkey's decision follows similar actions on Tuesday by the U.S., U.K., France and other major nations, The Guardian says is "the most significant" such move so far because Turkey is "Syria's northern neighbor and a former ally."

Turkey also went further than other nations by ordering all Syrian diplomatic staff to depart within 72 hours. Other nations have only ordered Syria's top diplomats to leave.

In a statement, Turkey's foreign ministry said "it is out of the question to remain silent and without any reaction in the face of this action, which amounts to a crime against humanity."

Friday in Houla, Syria, more than 100 people — many of them women and children — were killed. Most were at close range, execution-style, according to the U.N. The Assad regime has blamed "terrorists." United Nations officials, however, dismiss that claim and say there's ample evidence pointing to Assad loyalists.

It's estimated that as many as 15,000 people, most at the hands of government forces and paramilitaries, have been killed in Syria since protests against the Assad regime began in March 2011.

The U.N. Human Rights Council is expected to hold a special session Friday to discuss the massacre in Houla. As the BBC reports, Russia remains "categorically against" foreign intervention in Syria and believes it would be "premature" for the U.N. Security Council to take any new steps regarding the situation.

Former U.N. Secretary General Kofi Annan has been trying to broker a peace deal.

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